The preparation of suede on the surface of a silicon chip is a key link in the preparation of a polycrystalline silicon solar cell. The suede preparation effect directly influences the final conversion efficiency and the final rate of finished products of cell slices. As a polycrystalline silicon chip consists of crystalline grains in different crystal orientations and the crystal orientation of each crystalline grain is distributed optionally, in ordinary suede technologies, suede is formed on the surface of a polycrystalline silicon chip by means of the wet chemical corrosion of an acid solution. These suede preparation technologies based on the isotropic corrosion principle of an acid solution on silicon form, on surfaces of different crystalline grains of a silicon sheet, similar pit suede the shape and the appearance of which is irrelevant to orientations of the crystalline grains.
At present, the common acid solution used in industrial production consists of nitric acid, hydrofluoric acid and deionized water. The suede prepared with this acid solution is not desirable and has the following disadvantages: the suede is large in size and poor in uniformity, the color difference between different crystalline grains is obvious, there are deep etch pits of a black line shape in the macroscopic appearance of the suede, the reflection rate of the prepared suede is relatively high, and the stability of the suede prepared is not good. Thus, it will be of great significance to address the problems above by preparing suede through the addition of a suede preparation additive into an acid solution.